Act leader David Seymour says that, while the world is opening up, New Zealand is becoming a "hermit kingdom".
Writing a column for the Daily Mail, Seymour described a photograph he was sent of the Newmarket train station as "completely devoid of life", without its usual "hustle and bustle".
Seymour says that, two years since the pandemic began, "something close to normality has finally resumed for many across the globe" but that is not the case in New Zealand.
"Here in our far-flung corner of the Southern Hemisphere, isolated behind our still-sealed border, we endlessly push around a hamster wheel of ever more wearying rules and restrictions," the Act leader writes.
Seymour went on to slam quarantine rules - "a staggering isolation period of up to 24 days for those in households where someone has tested positive" - and the limits on gatherings at public events, which he described as "a devastating imposition on the entertainment industry in this, our peak summer season".
"You might think that only a devastating upward spiral of deaths and serious illness could justify continuing such measures, not to mention introducing new ones. Alas not. They were introduced last week after confirmation of just nine new cases of Omicron, largely centred on a family who contracted the virus on a trip to Auckland for a wedding from their home in the South Island," he continued.
The Act leader accuses Prime Minister Jacinda Ardern of being "committed as she apparently is to a policy of 'Zero Covid' at any cost".
"To coin the phrase of one of her predecessors, Sir John Key, her policies are turning us into a 'hermit kingdom'," he added.
"Thanks to these gruesome rules, weddings are being cancelled across the country and nightclubs haven't bothered opening up."
Seymour writes in his Daily Mail column that tourism in New Zealand "has been laid to waste" thanks to the two-year border closure, adding that those who do make it through the border have to stay in "a state-sanctioned quarantine hotel at their own expense, and where they are supervised by military personnel".
"It is desperately sad to watch the confident, free society I have always loved give way to this closeted, insular one, bound by what feels like ever-more authoritarian measures with no end in sight," Seymour wrote.
"To add insult to injury, we are effectively banned from testing ourselves for Covid, as happens all over the world.
"Only a 'trained tester' such as a medic or a pharmacist is allowed to do the job, and anyone who imports rapid antigen tests for home use could face up to six months in jail," he added.
"This is hardly in the spirit of the liberal, laid-back New Zealand the world once knew. It is little wonder that, weary of what feels like creeping authoritarianism and a never-ending marathon of restrictions, the population is kicking back."
The Act leader says "you can hardly blame disgruntled Kiwis for moaning that Lefties love nothing more than the excuse to impose a lockdown".
He accuses Ardern of using fear as a political tool and says many people are "losing their patience".
"While the rest of the world moves forward, it feels like we in New Zealand are moving backwards, reduced to look on enviously as you go about your business," he adds.